Features and Benefits:?Custom sizing: Use with Milwaukee Thick Wall 4" Core Bit (48-20-5125) and centering pin (48-20-5199)?Increased drilling precision: Reduces bit walk and improves bit stabilityIncrease your precision in masonry and concrete drilling with the Milwaukee? guide plate for thick wall core bit. You'll see reduced bit walk and improved bit stability when you use Milwaukee's durable plastic guide plate and centering pin (not included) for starting holes with your SDS plus rotary hammer drill.